Here we find a practical application of the instruction given in 1 Corinthians 14:6–12. If the point of spiritual gifts is to build up the church, and if only that which can be understood can build up, then the speaker in tongues must pray for the power to interpret.
The setting that Paul has in mind is that of the worship service. Tongues should be used in public worship only when they can be interpreted. (If interpretation is not possible, the speaker should remain silent; see 1 Corinthians 14:28.)
13 Therefore, one who speaks in a tongue should pray that he may interpret.